Complex systems comprising tens or hundreds of inter-related and inter-operating systems and subsystems, many which may be complex in there own right, present unique maintenance and service challenges. Examples of such complex systems include factories, major buildings, ocean going vessels, power generation plants, and aircraft to name a few. Complex systems and the inter-related and inter-operational nature of the systems and subsystems thereof often require equally complex and disciplined maintenance and service programs. These programs usually include documentation or records of observed or indicated irregularities or discrepancies and actions taken or services performed pursuant to resolution or prevention of such irregularities and discrepancies. This documentation is usually filled out, completed, or recorded by the service and maintenance personnel.
In the aircraft industry fault codes have more recently come to be used to provide a mechanism to summarize the set of symptoms or syndrome that is reported for each distinct aircraft fault condition. A fault code typically corresponds to a fault condition in a single system on the aircraft and can be used as the basis of fault isolation, material planning and deferral/criticality analysis. Fault Codes are a critical element of a “Fault Model” for an aircraft that can be used to support an automated diagnostic and maintenance support system.
For example Honeywell International Inc. builds an automated expert system called “AMOSS” (Aircraft Maintenance and Operations Support System) that uses fault codes as a standard element in structuring the maintenance activities for an airline and aircraft within that airline. For aircraft designed after the middle of the 1980's, the maintenance documents developed by the manufacturer include Fault Codes. However, aircraft designed prior to the middle of the 1980's (a large percentage of aircraft presently flying) did not include the Fault Code as a part of their maintenance documentation.
For those aircraft and other complex systems that have not employed fault codes or some similar standardization technique, the ability to modify or standardize maintenance and service programs based on historical data is limited since different service technicians are likely to describe similar observations and actions in different terms thus limiting the usefulness of historical information. The airlines have attempted to overcome this limitation through training to instruct their maintenance and service personnel to use various fault classification and reporting strategies for older aircraft. This adds complexity to the maintenance and service procedures, increases costs, and reduces the precision of planning and cost analysis activities. Clearly a need exists for methods and apparatus for developing standard fault codes based on historical data.